A standard shear has a frame normally formed of two massive plates formed with upper and lower horizontally throughgoing windows, the windows of the one plate being aligned with those of the other. These frames carry at each of these windows a respective abutment-forming fixed blade that has a shape corresponding to the type of workpiece being cut, that is flat for flat stock and shaped for profiled or solid-section stock. A working slide formed in line with the frame-plate windows with respective windows is vertically displaceable by means of a massive double-acting hydraulic ram between the two frame plates and in turn carries at each of the windows a blade that passes the respective fixed blade when the slide is dropped. Thus a workpiece to be cut is poked through the aligned windows at the appropriate station, and the actuator pushes down the slide to cut the workpiece between the respective blades. Such an arrangement is described in German patent documents Nos. 2,838,733, 2,838,735, and 2,940,635 and is sold under the trade name "Mubea Matic" by the assignee of the instant application.
Furthermore it is possible in such a machine to provide a secondary angle slide carrying one of the movable blades, so that as the main slide descends the angle slide, which is destined to cut upright profile material, moves at about 45.degree. to the vertical. Finally, it is also known to provide a puncher, riveter, or the like on the shear as described in application No. 193,670 filed Oct. 3, 1980 now U.S. Pat. No. 4,369,907, and marketed as a Mubea-Matic KBL 1300, so as to get the maximum versatility out of this big piece of equipment.
A holddown is provided on these machines to retain the workpieces in place against the respective fixed blades before the cut. This device has various adjustable parts that can be set to press the workpiece tightly against the fixed blade. Unfortunately such devices take up quite some room on the machine right around the critical blade area. When a blade must be changed it is therefore necessary to painstakingly remove the holddown system to gain access to the blades, and to laboriously remount it when the servicing is completed, something that is particularly onerous for a short workpiece run.